With the development of cloud application technologies, a cloud provides a variety of services for users. Users require that they can access services at any time and any place, including that a user remotely accesses a device in a local area network (for example, a home network) conveniently by using a remote device (also referred to as a “remote client”, for example, a mobile phone or a laptop computer) in a remote network.
An existing Universal Plug and Play Remote Access (Upnp-RA) technology implements an interconnection between a remote device and a device in a home network. The remote device is connected to the device in the home network through a secure transmission channel. A first basis for the Upnp-RA technology is the Simple Service Discovery Protocol (SSDP) protocol, and in a system structure of Upnp-RA, a Remote Access Discovery Agent (RADA) is used in a remote network and a home network to listen to a local SSDP message to discover an available device and a service status of the device. A second basis for the Upnp-RA technology is the Hypertext Transfer Protocol (HTTP) protocol, and in a system structure of Upnp-RA, a Remote Access Transport Agent (RATA) is used to implement transmission of information between a remote device and a device in a home network. The remote network and the home network implement synchronization of a current available device and a service status of the device by using their respective RADA Synchronization (RADASync). For example, when a service status of a device in the home network changes (for example, from available to unavailable), the home network implements update of the service status of the device by using RADASync, sends updated information to the remote network by using the RATA, and the remote network also updates the current service status of the device in the home network by using RADASync. However, the remote device needs to acquire address information of the device in the home network.
In addition, in the terms of ensuring security of remote access, a Secure Sockets Layer Virtual Private Network (SSL VPN) solution is relatively complex and needs support of an operator. A remote device needs to know an address of a Remote Access Server (RAS) in a local area network, and a user further needs to configure an address on the RAS, which is relatively troublesome and inconvenient.